The present invention generally relates to electrical connectors. The invention relates more specifically to an electrical connector having enhanced strain relief for signal-sensitive electronic equipment.
The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
The Small Computer System Interfaces (SCSI) were originally developed as a set of ANSI standard electronic interfaces to allow personal computers to communicate with peripheral hardware such as disk drives, tape drives, CD-ROM drives, printers, and scanners faster and more flexibly than previous interfaces. The original SCSI is now known as SCSI-1, which evolved into SCSI-2.
SCSI-3 consists of a set of primary commands and additional specialized command sets to meet the needs of specific device types. For example, the collection of SCSI-3 command sets is used not only for the SCSI-3 parallel interface but for additional parallel and serial protocols, including Fibre Channel, Serial Bus Protocol (used with the IEEE 1394 Fire Wire physical protocol), and the Serial Storage Protocol (SSP). The SCSI-3 protocol was designed to provide an efficient peer-to-peer I/O bus. Generally, the SCSI Parallel Interface (SPI) standards define the mechanical, electrical, timing and protocol requirements of the SCSI parallel interface to allow conforming SCSI devices to interoperate.
Connectors are the physical devices that are used to attach a SCSI cable to a SCSI device. Several different types of SCSI connectors are used to construct SCSI cables. SPI-2 defines a smaller version of an older high-density 68-pin connector. The desire for miniaturization and high throughput have been a driving force in the creation of new connector types.
The Very High Density Cable Interconnect (VHDCI) was introduced in the SPI-2 standard. VHDCI connectors evolved from the computer industry, mainly for disk drive interconnections, which are primarily internal to a chassis and therefore are protected. Networking implementations of VHDCI connectors, such as with high-speed, high-volume switching components, are subject to different demands than are connectors implemented for disk drives. For example, disk drives can tolerate a certain amount of signal interruption and lost bits of information, because the drive can simply and quickly re-read the relevant portion of disk without a noticeable impact to the user. However, in high speed switch implementations, often, no signal interruption is tolerable.
VHDCI connectors are blade connectors having two rows of flat contacts instead of pins. Thus, VHDCI connectors have a high pin density per unit length and good electrical characteristics at high throughputs. Consequently, VHDCI connectors are often used for implementations with electronic components that require high throughput and that have marginal space available on their interconnect panels. However, pin contacts are more physically compliant, thus, connectors with pins are generally considered to be more tolerant of misalignment than blade connectors.
Industry standard VHDCI connectors that are available are considered structurally weak. In particular, they are susceptible to off-axis forces. Off-axis forces are those that are not on the axis of the jackscrews (often referred to as thumbscrews). In fact, an industry-standard VHDCI connector has been measured to lose contact between some of the male and female connector contacts with a deflection of 0.065 inches at 1 inch away from the chassis to which it is connected. Consequently, electrical signals traveling through the connector can be interrupted.
Losing connector contact is an unacceptable situation with certain electronic components. If a signal interruption occurs with some electronic components, at a minimum, critical data is lost. In some instances, such as with high-speed network switches, the component typically crashes, thus requiring a subsequent reboot. A reboot operation often can last on the order of two minutes, which is unacceptable downtime for the switch fabric. Hence, such electronic components are considered to tolerate no signal interruption whatsoever. Indeed, the specification for a popular VHDCI connector allows for 1 xcexcsec (microsecond) of signal interruption. However, even this duration of signal interruption is considered unacceptable for certain electronic components.
One prior approach to overcoming the structural weakness inherent to conventional VHDCI connectors is to install a retrofit bracket to provide more rigidity to the connector. However, retrofitting components that are already provisioned in the field is not a desirable or practical solution.
Based on the foregoing, there is a clear need for an improved electrical connector for signal-sensitive electronic equipment. In this context, signal-sensitivity refers to the equipment""s tolerance to signal interruption. Further, there is a specific need for such a connector in the context of a low-profile Very High Density Cable Interconnect.